The function given is $y = 5x - 2$. Since this is a linear function (a polynomial of degree 1), the domain of a linear function is all real numbers. This is because there are no restrictions such as divisions by zero or square roots of negative numbers that would limit the values $x$ can take.

So, the correct answer is B. Domain: All real numbers.

Would you like more details on how domains are determined? Here are five related questions:

1. What is the domain of a quadratic function, such as $y = x^2 + 3x + 1$?
2. How do you find the domain of a rational function, like $y = \frac{1}{x-2}$?
3. What is the domain of a function involving square roots, such as $y = \sqrt{x-4}$?
4. Can a piecewise function have different domains for different parts?
5. How does the domain change for logarithmic functions like $y = \log(x)$?

Tip: Always check for divisions by zero or square roots of negative numbers when determining the domain of more complex functions!